Expansion controlling piston construction



1 July 4, 1944.

A. M. ALEXANDRESCU EXPANSIQN CONTROLLING ,PISTON CONSTRUCTION Filed Feb. 18, 1941 6 Sheets-Sheet l July 4, 1944. A. M. ALEXANDRESCU EXPANSION CONTROLLING PISTON CONSTRUCTION Filed Feb. 18, 1941 6 Sheets-Sheet 3 Gtto negS.

July 4, 1944.

A. M. ALEXANDRESCU EXPANSION CONTIROLLINGZPISTON CONSTRUCTION Filed Feb. 18, 1941 s sheets-sheet- 4 A. M ALEXANDRESCU 2,352,592 7 EXPANSION CONTROLLING PISTON CONSTRUCTION Filed Feb. 18,. 1941 e Sheets-Sheet 5 Inventor 15. M. flhzwzdrarca;

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UNITED STATES ,PATENT OFFICE EXPANSION CONTROLLING PISTON CONSTRUCTION Alexander M. Cleveland, om Application February is. 1941. Serial No. 379.522

4 Claims.

The .present invention relates to pistons and more particularly to an expansion controlling piston construction, and is an improvement over my Patents Nos.- 2,147,956 dated February 21,

1939, 2,195,552 dated April 2, 1940, 2,200,015 dated May 7, 1940, and is a continuation in part of my co-pending application No. 77036 filed April 29, 1936 and entitled improvements in Piston and ring construction.

Animportant object of the present invention is to provide a piston construction in which the expansion and contraction of the skirt portion may be controlled.

A further object of the invention is to provide a piston construction provided with an improved lubricant inlet and outlet..

A still further object of the present invention is to provide a simple diagram for grinding the .skirt portion by means of a cam grinder.

A still further object of the invention is to provide a simple manner of forming the skirt portion and the oil grooves of the piston Head.

Another object of the invention is to provide a more permanent lubrication in the skirt portion to prevent damage to the cylinder and other parts, and to prevent the skirt from digging or scoring the cylinder wall.

, 'Another object of the invention is to provide for the grinding of the skirt portion the same size at the top and bottom or a fraction larger at the top and smaller at the bottom.

Another object of the invention is to simplify the machining of the piston and thus lowering the cost of production; this is done by the proc- With the foregoing and other objects in view, the invention will be more fully described hereinafter, and will be more particularly pointed out in the claims appended hereto. In the drawings wherein like symbols refer to like or corresponding parts throughout the several views.

Figure 1 is a front elevational view of the piston and showing the improved lubricating piston skirt construction. I

1 Figure 2 is a central vertical'sectional view taken along the line 2-2 in Figure 1.

Figure 3 is a central vertical sectional view of the piston shown in Figure 1 before. being machined.

Figure 4 is a horizontal sectional view taken along the line H of Figure 2.

Figure 5 is a clearance diagram for grinding the piston skirt and giving the necessary dimensions.

Figure 6 is a front eievational view of a modified form of the piston shown in Figure 1.

Figure 7 is a central vertical sectional view taken on the line l-I of Figure 6.

Figure 8 is a horizontal sectional view taken on the-line 8-0 of Figure 7 looking up.

Figure 9 is a horizontal sectional view taken on the line 8-0 of Figure 7 but looking in the opposite direction from Figure 8 or down.

Figure 10 is a central. vertical sectional view of the piston shown in Figure 6 before being machined.

Figure 11 is a front elevational view of a further modified form of the invention.

Figure 12 is a horizontal sectional view taken on the line l2-l2 in Figure 11. a

Figure 13 is a rear eievational view of the piston and shown in Figure 11.

Figure 14 is a central vertical sectional view taken on line "-44 in Figure 11. v

Figure 15 is a transverse sectional view taken on the line li-li of Figure 14.

Figure 16 is an enlarged front elevational view showing the manner of producingdoubl'e lubricating openings in the front skirt portion of the piston shown in Figure 11.

Figure 17 is an enlarged front elevational view showing the manner of producing double lubricating openings in the rear skirt portion of the piston shown in Figure 13.

Figure 18 is a modified form of the openings shown in Figure 16.

Figure 19 is an enlarged front elevational view showing a slight modification in producing the openings shown in Figure 11.

Figure 20 is a fragmentary vertical sectional view taken through a cylinder and piston and showing a further modified form of the pistons shown in Figures 1-6 and 11.

Figure 21 is a horizontal sectional view taken on the line 2l-2l of Figure 20.

Figure 22 is a fragmentary vertical sectional view taken through a cylinder and piston and showing another modified form of piston and skirt.

Fi gure 23 is an enlarged front elevational view taken on the line 23-28 of the modified form of piston shown in Figure 22. I

Figure 24 is a fragmentary vertical section taken through a cylinder and piston and showing g the movement of the lubricant.

Figure 25 is a fragmentary vertical along the line 25-45 of Figure 24, and

Figure 26 is another fragmentary vertical section section through the piston before being machined.

Referring more particularly to the drawings and the ring grooves at I2. In Figures 2, 3, and

4 the usual bosses I: are shown which receive the wrist pin in a manner commonly known'in this art. a

The piston skirt I is formed with two openings i4 and I lying at substantially diametrically opposite portions of the skirt. They are both arranged in areas of the skirt III which are at right angles, or approximately right angles,

to the axis of the bosses I 8 or the axis of the wrist pin which occupies such bosses.

The openings I4 and I5 pass entirely through the walls of the skirt in as best seen in Figures 2 and 3 so that such openings be upon both inner and outer surfaces of the skirt wall and they permit free passage of lubricant or oil from the interior of the piston into which such oil is splashed by the action of the cranks from v the crank case, through the skirt wall where this oil or lubricant spreads over the entire surface of the skirt portion in its travel up and down on the cylinder wall.

By an examination of Figures 1 and 2 it will be seen that the opening i5 which lubricates the back or rear portion of the cylinder has its upper and lower walls l8 and i1 inclined in such a way that they converge inwardly. The walls l6 and i1 diverge outwardly towards the outer surface of the piston skirt and thus form wide mouths for the spreading of lubricant upon the cylinder walls.

The shape of the opening l5 may be elliptical or oval as shown in Patent No. 2,147,956 or may assume any shape having the characteristics referred to. I Theconfiguration of the opening i4 is substantially of heart shape, the upper portion of the heart terminating into two concentrating points l8 and i9 which are provided with inclined wall portions. The upper portion' of the skirt I0 is,

as shown in Figure 1, provided with a vertical slot which bisects the concentrating points i8 and i9 ofthe opening ll. In the downward movement of the piston the parts l8 and i9 with their associated walls prevent the lubricant from entering the slot 20 but the skirt is lubricated in the upward movement of the piston through the opening II and its inclined wall 2|.

Referring now to Figures 2, 3 and 4 it will be seen that the'ring column on top of the piston i l is connected to the skirt ill by the connectors 22 and 23, the center ribs 24, 25 and by the front' ribs 26 and 21. These front ribs 26 and 21 play an important role because, as seen in Figure 4, at the front of the skirt they have a 100 radius while the ring column above is approximately 74 closed. Between the top of the piston ll of oil under the oil rings on the downward movement of the piston.

An examination of the diagram illustrated in Figure 5 discloses the manner of cam grinding a piston skirt. As denoted by the dimensions forming a part of this figure, such grinding procedure will result in a large bearing at the back side of the skirt A whereas the front or slot side B will be provided with a small bearing. 'I'he reason for this is, as shown in Figure 5, that there the skirt is relaxing more at'the slot side due to heat tension. As illustrated in Figure 5, the figures thereon are those applying when the piston is cold but when the piston is hot, both the front and'rear sides will have approximately 90 bearings on the cylinder wall.

In other words the relaxation of the skirt is greater at the side provided with the slot but once expanded by heat the bearing of the skirt and the skirt i0 is the skirt channel skirt which permits the skirt to relax under heat tension and also permits lubrication of the skirt in the upward movement of the piston. At the same time it prevents building up of a-hydraulic force will be equal on both the front and rear sides. The construction disclosed permits controlling the expansion and contraction of the piston, lu-

bricates the cylinder wall and skirt from "the inside at all high speeds. As a result the cylinder will be kept smooth and round for more lasting and better compression.

The dimensions of grinding the skirt as in Fig. 5 is bound to be changed in accordance with the metal or composition (alloy) used to produce the piston.

A further advantage is that the lubricant concentrating at the points l8 and I8 prevents the oil from running into slot 20 of the skirt i0. Another advantage is that when the piston is cast and before being machined, sharp comers 29 are provided as illustrated in Figure 3. This assists in producing the top of skirt channel 28 which eliminates cutting operations heretofore necessary in forming this channel and such elimination results in lowering the cost of production.

In addition the provision of channel 28 prevents hydraulic oil pressure under the oil ring when the piston is operating rapidly or at high speed.

The charging and discharging channel 30 located above the oil ring prevents the suction intake from drawing oil up from the oil ring and maintains the proper lubrication for the top rings.

Inthe arrangement disclosed, the ribs and connectors permit a more permanent connection between the skirt and piston or ring column.

Referring now to the modification illustrated in Figures 6, '7, 8 and 9 the piston thereon shown is of the force feed type in .which the lubricant slides directly from the interior of the skirt on to the cylinder wall.

The skirt is denoted by the numeral 3|, the piston head by the numeral 32 and the piston rings by .the numeral 33. In Figure 9 the usual bosses 34 are shown which receive the wrist pinin the well known manner and the piston recipfrocates in the cylinder 35 as is well known in the art.

By referring to Figure 6 it will be seen that the skirt 3i is provided with substantially vertical slots 36 and 21 communicating with the skirt channel 38. Reinforcing ribs 39 for the rear part of the piston and similar ribs 40 for the front of the piston are provided. The usual central and front ribs similar to Figure 1 are also provided as shown by the numerals 4| and 42.

Now as particularly seen by inspecting Figures 6, '1 and s the skirt is provided with lubricant openings 43 at the'front and rear thereof. As shown in Figure 6, the preferred configuration of the openings is oval with inclined outer wall portions 44 and 45 and slightlysmaller inner inclined wall portions 46 and 41. This particular shape of opening and inclination of the walls thereof is advantageous to the force feed type of piston illustrated. The lubricant is concentrated on the walls It and 45 of the opening 48 as is obvious.

The casting shown in Figure 19 is provided with sharpcorners 88 for a purpose later to be described. The skirt channel 88, the ring grooves and the charging and discharging channel 890 are all cut at the same time. Thus when the skirt channel 38 is cut the slots 86 and 61. merge or communicate with each other and this method of cutting eliminates several steps now required in the production of'pistons'as the slots 36-31 are produced by the casting method.

As seen in Figure 8, the ribs 42 and 39 close the gap at the ring column to 74 on each side. Now an' inspection of this figure will reveal that the skirt opening is 90 on the rear side, about 199 on the front side above the slots 36, 31 and about 124 at the bottom of the slots. The skirt of the present construction may be ground in the manner illustrated \in the diagram of Figure 5, the piston when hot will have a bearing of about 90 on each side as previously pointed out.

Referring now to the construction shown in Figures 11 to 19, there is illustrated a piston head 29, and skirt portion 59 ha'ving the usual bosses Ribs 52, 53 and 54 are provided as in the constructions heretofore mentioned and for similar purposes.

The skirt portion is provided with a front lubricant opening 55 as shown in Figure 11 and a rear lubricant-opening 56 as shown in Figure 13.

As shown in Figure 11 the opening 55 is substantially oval with separated'head portions 51, 58, 59,

' and 69 which is medially separated by a slot 6|.

This 'slot 6| terminates at its upper portion in the skirt channel 62 while its lower portion extends beyond the opening 55 and terminates in a keyhole configuration 63.

The lubricant openings 55 and 56 are of the reservoir type which carry the lubricant up and down at the highest speed of the piston. As shown in Figure 11 the slot 6| extended beyond the opening 55'and to prevent the lubricant from running into slot 6|, it was necessary to provide the four concentrating points 51, 58, 59 and 69. On the downward movement of the piston the lubricant is forced between the skirt and cylinder wall by the concentrating points 51 and 58 and in the upward movement ofthe piston again is forcedin, this time by the points 59 and 69. The rear of the piston skirt is lubricated by the concentrating points 64 and 65 of the opening 56.

The ring column is connected to the skirt in the same manner as heretofore described in the other forms of pistons by connector ribs, etc. with the exception of additional slots 66 and 61 in the rear of the skirt 59. Expansion and contraction is controlled as heretofore described. As in the other forms of the invention the skirt can be ground with the diagram of Figure 5 or 12 all depending on the alloy used in producing the piston.

Figures 16, 1'7, 18 and 19 illustrate how various lubrication openings for the skirt portion may be formed. In Figure 16, the skirt is provided with front lubricating openings to and 69, the opening 68 being cut into the skirt of Figure 11 at a suitable point below the skirt channel 62 while the opening 69 is located in the plane of the key hole 63 of 'slot 6|,in Figure 11. Accordingly Figure 16 shows the openings 68 and 69 communicating with a slot I9. The concentrating points II, 12, I3. ll, 15,16, and 11 serve to keep the lubricant out of the slot 19 in the manner heretofore described.

In Figure 17 is illustrated a long skirt with rear lubrication openings 78 and I9 with concentrating points 89, 8|, 82 and 83 which function similarly. to the'concentrating points referred to in the other forms of the invention. Tucse openings are suitably located in asis obvious.

Figure 19 is a modified form of the opening disclosed in Figure .11. Instead of a single opening across the slot 6|, twin openings 81 and 88 are provided in the skirt. The intervening metal 89 between the openings and the slot serves as a reinforcement similar to that of Figure 18.

It is obvious that in all forms of the openings illustrated in Figures 16, 17, 18 and 19, concentrating points for the lubricant are provided.

Referring now to the modification illustrated in Figures 29', 21, 22 and 23, the piston head and skirt are connected by connectors and r.bs in the same manner as described with reference to the other forms of the invention. The piston illusthe rear area of the skirt trated in the instant figures is of heavy duty type and additional ribs are provided as well as a straight'down connector to withstand the heavy strain to which they are subjected. A slot 99 is cut in one side of the skirt from top to bottom and the skirt is further provided with expansion controllers 9| and 92. The controller illustrated in Figures 20 and 21 is out in two but in Figures 22 and 23 it is produced in-the casting separate from one another.,

The skirt of the instant piston is cam. ground with a very small clearance at the wrist pin holes and is almost round, fitting the cylinder with a small clearance. As the piston becomes heated, the controllers 9| and 92 permit the skirt'to relax and prevent its collapseat the slot 99. I

The openings 93, 94, and 96 permit the corners of the skirt to keep relaxing under heat tension. Lubrication through openings 91, 98 and 99 is of the force feed type and circulates around the skirt to be discharged in the piston by openings I99 and MI.

The construction illustrated in Figures 24, 25 and 26 is primarily intended for use in airplanes although of course not limited to such use. This type of construction has the usual head I92 and skirt I93 with front and back lubricant openings I94 and I95 in the center of the skirt. The top of skirt lubricating channel I96 permits the lubri cant to slide in and out of the same and prevents the building up 'of a hydraulic pressure under the oil ring. The openings I9'I- communicate with thechannel I99 which prevents oil suction from oil ring I98 in the intake stroke. In the downward movement of piston the oil from. the bearings splashes up into the piston skirt over the beveled walls 2 and H3. When the piston goes down the oil collected on the wall 3 is forced in groove Ill through openings Ill and II! is indicated by the arrows H6- and Ill in Figure 24. Any excess of oil in the space II. is returned to the crankcase by the opening ill formed in the skirt casting. This type of lubrication is very efflcient for the present speedy type of engine and prevents scoring, helps. the rings keep compression withresulting more power at less expense.

As illustrated in Figure 26, the groove H8 is cast from the inside of the skirt. This samemethod of casting is used in the forms of the invention illustrated in Figures 20 and 22. By this method and by the groove H is produced the opening I functioning to force feed-oil and the sliding over oi the lubricant in between the skirt and cylinder wall.

.In all forms of the invention there has been illustrated a piston in which the expansion and contraction may be controlled. This permits a more lasting lubrication between the skirt and cylinder and prevents damage to the skirt and other parts by scoring'etc. Due to the possibility of cam grinding the skirt in the manner proposed eliminates the scoring or biting of the cylinder by the skirt. The skirt may be ground substantially equal at the top and bottom and this keeps the rings on more securely and allows greater compression.

A further advantage of the present construction is the elimination of, several operations in the machining steps which cuts the cost of the piston. This is primarily accomplished by the provision of sharp corners in the castings, in addition to the ribs connectors etc. Other advantages are believed obvious from the foregoing description.

It is of course understood that the material used may be better suitable to work for which the piston is intended. Thus it may be cast in iron, aluminum, steel, alloy or any desired material.

It is obvious that various changes and modifications may be made in the details of construction and design of the above described embodiments of the invention without departing from the spirit thereof, such changes and modifications being restricted only by the scope of the following claims.

What is claimed is:

1. An improved piston comprising a piston head and skirt, said skirt having a substantially cylindrical wall with an outer surface to engage the cylinder and with an inner surface to receive oil splashed up from the crank case, said skirt having an opening through its cylindrical wall,

the opening having upper and lower walls, said lower wall being inclined inwardly of the skirt, said upper wall being inclined in two directions, one component direction being on a line converging inwardly of the skirt mutually with saidlower wall, the other component being on an inclination converging from the outer ends of the openthe cylinder and with an inner surface to receive oil splashed up from the crank case, said skirthaving an opening through its cylindrical wall, the opening having upper and lower walls, said lower wall being inclined inwardly of the skirt, said upper wall being inclined in two directions. one component direction being on a line converging inwardly of the skirt mutually with said lower wall, the other component being on an inclination converging from the outer ends of the opening inwardly convergent to the central portion of said opening, and a substantially vertical expansion slot extending through the skirt .from the upper portion of the piston and through the opening at substantially the central portion of the opening, thus dividing the--upper wall into two substantially half portions, the upper edges of said half portions being curved and extending downwardly to the points where such curved edges merge with said expansion slot.

3. An improved piston comprising 'a piston head and skirt, said skirt having a substantially cylindrical ,wall with an outer surface to engage the cylinder and with an inner surface to receive oil splashed up from the crank case, said skirt having an opening through its cylindrical wall, the opening having upper and lower walls, said upper and lower walls being inclined in two directions, one component direction being on a line converging inwardly of the skirt, the other component being on an inclination converging from the outer ends of the opening, and a substantially vertical expansion slot extending through the skirt from the upper portion of the piston and through the opening at substantially the central portion of the opening, thus dividing the upper and lower walls into two substantially half portions, the upper walls of said half portions being curved and extending downwardly to the points where such curved edges merge with said expansion slot.

4. An improved piston comprising a piston head and skirt, said skirt having a substantially cylindrical wall with an outer surface to engage the cylinder and with an inner surface to receive oil splashed up from the crank case, said skirt having an opening through its cylindrical wall, the opening having upper and lower walls, said upper and lower walls being inclined in two directions, one component direction being on a line converging inwardly of the skirt, the other component being on an inclination converging from the outer ends of the opening, a second opening below and spaced from said first mentioned opening, said second opening having upper and lower walls, said lower wall being inclined inwardly of the skirt, said upper wall being inclined in two directions, one component direction being on line converging inwardly of the skirt mutually with said lower wall, the other component being on an inclination converging fromthe outer ends of the opening inwardly convergent to the central portion of said opening, and a substantially vertical expansion slot extending through the skirt and through said first opening into the second opening, thus dividing the upper and lower walls of the first opening and the upper wall of the second opening into substantially half portions, the upper edges of said half portions being curved and extending downwardly to merge with said slot.

ALEXANDER. M. ALEXANDRESCU. 

